A major environmental concern today is the increase of the “carbon footprint” of human activities. The “carbon footprint” is the amount of carbon dioxide (CO2) produced by an entity due to the use of carbon-containing fuels or the like. The carbon dioxide that is inevitably formed from the combustion or degradation of carbon-based fuels, materials or any live processes is a major concern because it contributes significantly to the change of our climate by causing harmful global warming. When any carbon-containing compound is combusted or degraded, carbon dioxide is formed. Carbon dioxide is an environmentally harmful greenhouse gas. The use of coal or other fossil fuels, and power plants burning such fuels, cement plants, breweries, transportation sector, etc., produce annually in excess of 30 billion tonnes of carbon dioxide. Various other activities such as agriculture, live processes and discharge of varied natural sources also produce large amounts of carbon dioxide. While as much as half of the carbon dioxide related to human activities is absorbed or recycled by nature, such as the oceans and photosynthesis processes, the remaining amount still greatly overloads and upsets the terrestrial carbon dioxide balance.
One of the current major challenges for humankind is how to dispose of such harmful excessive greenhouse carbon dioxide emissions to mitigate their contribution to global climate change (or global warming). The Kyoto and Copenhagen international conferences attempted to find solutions to limit CO2 emission due to the excessive burning of fossil fuels or other anthropogenic activities but resulted only in regulatory and economic (carbon quotas, taxes, cap and trade) approaches. Also, widespread efforts are being made to try to reduce the use of carbon-containing fuels and materials and to replace fossil fuels with non-carbon-containing energy sources. It is recognized that non-carbon-containing sources of energy, such as alternative sources, e.g., hydro, geothermal, solar, wind, as well as others, and atomic energy should be used more. Further, an essential aspect of our carbon future is the fact that fossil fuel resources are limited and will be used up by increasing demand of population growth and industrialization. Relatively easily accessible oil and natural gas may only last this century, whereas more abundant coal another two centuries. In the foreseeable future, however, fossil energy sources will continue to be utilized because of its ready availability and relatively low cost compared to the alternatives. Thus, the need remains for disposal of such emissions.
One way to address the harmful effects of human-generated carbon dioxide emissions is the capture and sequestration (or storage) of carbon dioxide in depleted oil and gas fields or coal mines, at the bottom of the sea or underground in caverns or other sealed cavities. This is generally referred to as carbon capture and sequestration (“CCS”). There are, however, obvious limitations of this approach. Sequestration is a costly process that does not provide any economic benefit and at best is only a temporary solution. Volatile carbon dioxide can leak out from subterranean or under-the-seas storage facilities even in the best selected geological formations and location, such as depleted oil fields or the bottom of the seas or lakes. Sequestered (or stored) carbon dioxide also is very susceptible to geological disturbances, such as earthquakes, slides, and volcanic eruption. Geological disturbances can cause the instant release of huge amounts of stored carbon dioxide on a massive scale and have a deadly effect, since carbon dioxide is heavier than the air and can suffocate living creatures in the proximity of large scale releases of carbon dioxide. Also, even if stored carbon dioxide does not leak and converts to carbonates over time (which is how limestone is formed in nature over eons), the extremely long time needed for such carbonation renders carbon dioxide sequestration only a temporary storage solution on the human time scale. Furthermore, CCS renders a significant part of the Earth's carbon resources lay dormant and of little use. Thus, improved solutions to address and reduce carbon dioxide emissions are needed.